Internal line-up clamp for pipe lines

ABSTRACT

actuated drive means for propelling the clamp axially forwardly through a pipeline section together with associated control means for automatically stopping, reversing and positioning the clamp at the open end of the welded-in pipe section in position to receive the next set-in pipe section. The invention is explained in detail hereinbelow by reference to a specific clamp apparatus incorporating the features of the invention. Such apparatus is not meant to be limiting inasmuch as it will be understood that it constitutes but one of the ways in which the principles of the invention may be applied. An internal line-up clamp which incorporates a pair of interconnected but independently operable clamping assemblies, each of which includes a set of radially movable pipe engaging shoes adapted to clampingly engage the inner circumferences of a pair of pipe sections in the zones adjacent their ends. At least two axially movable pneumatic actuators are operatively associated with each set of clamping shoes in a manner such that axial movement of the actuators effects radial movement of the shoe set with which they are associated. The clamping assemblies are interconnected by a plurality of axially extending rods which are adapted to maintain the assemblies in axial alignment while permitting them to be moved axially with respect to each other a limited distance. A fifth pneumatic actuator means is provided for effecting such reciprocal axial movement of the clamp assemblies. This invention relates to a line-up clamp for use in the welding of pipelines and, more particularly, to a pipe line-up clamp for clamping the internal surfaces of a pair of adjacent pipe ends and positioning and maintaining the pipe ends in precisely aligned relationship for welding by either manual or automatic welding means. In the construction of pipelines, a large number of individual pipe sections are welded together in end-to-end relationship. It is the usual practice to utilize an internal line-up clamp to align adjacent pipe ends prior to welding and maintain them in aligned position during the welding operation. Many such internal pipe line-up clamps are known and in commercial use. However, the known clamps are deficient in many respects. For effective welding, particularly with automatic welding equipment, the pipe ends must not only be coaxial but the pipe walls must be accurately aligned around their entire circumferences. Steel pipe sections used in the pipeline construction industry are not always exactly cylindrical nor are the ends precisely square. Also, during transportation to and handling on the job site, the pipe sections are often bent out of round. As a result, when a set-in pipe section is positioned in end-to-end relationship with the open end of the welded-in portion of the pipeline, the adjacent pipe ends often exhibit different degrees of roundness and, also, the end faces do not abut even though the pipes may be coaxial. Conventional line-up clamps are generally not capable of exerting a sufficiently great pressure upon the adjacent ends of out-of-round pipe sections to bring them into precise alignment, particularly in the case of the relatively large diameter pipes which are becoming increasingly common in the pipeline industry. In addition, in using the prior art clamps it is often difficult to bring the end faces of the pipe sections in to proper abutting relationship since the set-in pipe is positioned entirely by mechanical means external to the clamp itself, e.g. by manipulation of the set-in pipe support sling and movement of the side-boom tractor carrying the set-in pipe. This proceDure, of course, is tedious and time consuming particularly where the end faces of pipe sections are not exactly square. For these reasons particularly, the prior art line-up clamps are generally unsuitable for use in conjunction with automatic welding equipment which requires extremely precise alignment of the pipe ends and, preferably, accurate spacing between the adjacent surfaces which are to be joined. The prior clamps also are are generally difficult to manipulate and position within the pipeline section preparatory to clamping each new section in place for welding. Moreover, difficulty is often encountered in moving the prior line-up clamps through curved pipe sections because of the very small clearance normally provided between the pipe engaging clamping shoes and the internal surfaces of the pipe. Although many attempts have been made to overcome the foregoing and other disadvantages of the prior art clamps, non, as far as is known, has been provided which has been entirely satisfactory in commercial operations. Accordingly, it is an object of the present invention to provide an apparatus for axially aligning adjacent pipe ends which is capable of exerting very high radial forces on the inner circumference of the pipe ends to force each into a truly circular configuration. Another object of the invention is the provision of apparatus for aligning pipe ends which is capable of clamping the end of a set-in pipe and drawing it into abutting, axially aligned relationship with the pipe end to which it is to be joined. Another object of the invention is to provide an internal pipe line-up clamp which may be quickly and automatically positioned and clamped at the end of the welded in-pipe section in position for receiving the set-in pipe section. Still another object of the present invention is to provide a pipe line-up clamp which functions to (a) securely clamp and round out the open end of the welded-in pipe in an initial clamping action, (b) clamp the set-in pipe end after it is brought into rough end-to-end alignment with the welded-in pipe, (c) draw the set-in pipe towards the welded-in pipe to bring the end faces of the two pipes into engagement, (d) securely clamp and round out the end of the set-in pipe in a secondary clamping action and, finally, (e) back-space the end face of the set-in pipe a predetermined distance of the welded-in pipe end face to provide a uniform gap between the adjacent pipe end faces while still maintaining the pipe walls in accurate alignment. Yet another object of the present invention is the provision of apparatus for aligning pipe ends which incorporates pipe-engaging clamping elements capable of relatively large retractive radial movement from an operative to a non-operative position thereby permitting the clamp to traverse curved pipe sections without damage to the pipe or clamping elements. A still further object of the invention is to provide apparatus for positioning and aligning pipe ends which is relatively inexpensive to manufacture, simple to operate and rugged and durable in use. According to the invention, these and other objects and advantages are obtained by an internal line-up clamp which incorporates a pair of interconnected but independently operable clamping assemblies, each of which includes a set of radially movable pipe engaging shoes adapted to clampingly engage the inner circumferences of a pair of pipe sections in the zones adjacent their ends. At least two axially movable pneumatic actuators are operatively associated with each set of clamping shoes in a manner such that axial movement of the actuators effects radial movement of the shoe set with which they are associated. The clamping assemblies are interconnected by a plurality of axially extending rods which are adapted to maintain the assemblies in axial alignment while permitting them to be moved axially with respect to each other a limited distance. A fifth pneumatic actuator meanS is provided for effecting such reciprocal axial movement of the clamp assemblies. The double actuator means associated with each set of pipe engaging shoes enables each shoe set to be actuated independently and it also permits imposition of clamping forces which can be selectively increased through at least two stages to a level sufficiently great to round out large diameter, high strength pipe sections without difficulty. In a preferred embodiment of the clamp, the high clamping force capability of the compound actuator means is transmitted to the pipe engaging clamping shoes by means of a plurality of tandem pivot links which are adapted for retraction radially inwardly when the clamp is in a nonoperative or pipe-traversing state, thus ensuring ample clearance between the clamp shoes and the inner wall of the pipe through which it is traversed. An another preferred aspect, the clamp incorporates pneumatically

United States Patent Bradley et a1.

[54] INTERNAL LINE-UP CLAMP FOR PIPE LINES [72] Inventors: Edmund G. Bradley, 7 Personna Boulevard, R.R. 2, Gormley, On-

tario; Reginald P. Whittingham, R.R. 2, Markham, Ontario, both of Canada [22] Filed: May 26, 1970 [21] Appl. No.: 40,683

[52] US. Cl. ..29/252, 29/272, 269/17,

269/34, 269/48.l [51] Int. Cl. ..B23p 19/04, B23q 3/18, B25b H18 [58] Field of Search ..269/17, 34, 48.1; 29/252, 272,

[56] References Cited UNITED STATES PATENTS 3,561,320 2/1971 Nelson ..269/48.l X 2,525,680 10/ l 950 lngemarson ..269/34 2,594,000 4/1952 Elliott ..269/48.l 2,615,413 10/1952 Adams ..269/34 3,229,972 1/1966 Cunningham ..269/48.l 3,044,431 7/ 1962 Cummings ..269/ 34 3,197,195 7/1965 Work ..269/17 X 3,270,411 9/ 1966 Thomas ..269/48.l X

[451 Oct. 24, 1972 Elliott ..29/272 Primary Examiner-Wayne A. Morse, Jr. Att0rney-Frank I. Piper and Arne l. Fors [5 7] ABSTRACT An internal line-up clamp which incorporates a pair of interconnected but independently operable clamping assemblies, each of which includes a set of radially movable pipe engaging shoes adapted to clampingly engage the inner circumferences of a pair of pipe sections in the zones adjacent their ends. At least two axially movable pneumatic actuators are operatively associated with each set of clamping shoes in a manner such that axial movement of the actuators effects radia1 movement of the shoe set with which they are associated. The clamping assemblies are interconnected by a plurality of axially extending rods which are adapted to maintain the assemblies in axial alignment while permitting them to be moved axially with respect to each other a limited distance. A fifth pneumatic actuator means is provided for effecting such reciprocal axial movement of the clamp assemblies.

12 Claims, 22 Drawing Figures PATENTED um 24 1972 SHEET Gilli-'10 vmv hhv IN'VENIOR. EDMUND s. BRADLEY REGINALD PWITTINGHAM BY Pmemmwwmz V 3.699.635

SHEET UEUF 10 O) V C E (o $9 mm LL 1. mm w (G v ("7 (")CU mm 0 (\l O Q o INVENTOR.

. EDMUND G. BRADLEY REGINALD F? WITTINGHAM I IQ BY I l g, Z 7

N II

SHEET UQUF 10 I N VENTOR.

INVENTOR.

EDMUND G. BRAD Y REGINALD F. WITTI HAM I PATENTED'ucr-u m2 1,,- IIIIIIIIIIIIIIIIITT 11111111":

SHEET OBUF 10 INVENTOR.

E UND G. RADLE YR NALDF? TTING M QM P PATENTEDBBTZMQYZ 2 3.699.635

- 'SHEET D7UF1O INVENTOR.

EDMUND GNBRADLEY REGINALD P. WITTINGHAM PAIENTEMHM m 3.699.635 SHEET UBUF 10 FIG. 13

'1 IN'VENIOR. EDMUND cs. BRADLEY REGINALD e WITTINGHAM 1115111500112 1912 3,699,635 SHEET USUF 10 331 343* 1 Y 321 331 !3 3| 1 l l I l/ y I0 328' 341 1 33031211 311 FIG. 18 E912 INVENTOR. EDMUND G. BRADLEY REGINALD P.' WITTINGHAM PATENTEDucIu I972 SHEET 100F'10 FIG. 20

451 440 FIG. 21

416 413 FIG. 22

410 41 4 JNVEN'TOR.

EDMUND G. BRADLEY REGINALD P WIITTINGHAM INTERNAL LINE-UP CLAMP FOR PIPE LINES This invention relates to a line-up clamp for use in the welding of pipelines and, more particularly, to a pipe line-up clamp for clamping the internal surfaces of a pair of adjacent pipe ends and positioning and maintaining the pipe ends in precisely aligned relationship for welding by either manual or automatic welding means.

In the construction of pipelines, a large number of individual pipe sections are welded together in end-toend relationship. It is the usual practice to utilize an internal line-up clamp to align adjacent pipe ends prior to welding and maintain them in aligned position during the welding operation. Many such internal pipe line-up clamps are known and in commercial use. However, the known clamps are deficient in many respects.

For effective welding, particularly with automatic welding equipment, the pipe ends must not only be coaxial but the pipe walls must be accurately aligned around their entire circumferences. Steel pipe sections used in the pipeline construction industry are not always exactly cylindrical nor are the ends precisely square. Also, during transportation to and handling on the job site, the pipe sections are often bent. out of round. As a result, when a set-in pipe section is positioned in end-to-end relationship with the open end of the welded-in portion of the pipeline, the adjacent pipe ends often exhibit different degrees of roundness and, also, the end faces do not abut even though the pipes may be coaxial.

Conventional line-up clamps are generally not capable of exerting a sufficiently great pressure upon the adjacent ends of out-of-round pipe sections to bring them into precise alignment, particularly in the case of the relatively large diameter pipes which are becoming increasingly common in the pipeline industry. In addition, in using the prior art clamps it is often difficult to self, e.g. by manipulation of the set-in pipe support sling and movement of the side-boom tractor carrying the set-in pipe. This procedure, of course, is tedious and time consuming particularly where the end faces of pipe sections are not exactly square. For thesereasons particularly, the prior art line-up clamps are generally unsuitable for use in conjunction with automatic welding equipment which requires extremely precise alignment of the pipe ends and, preferably, accurate spacing between the adjacent surfaces which are to be joined.

The prior clamps also are are generally difficult to manipulate and position within the pipeline section preparatory to clamping each new section in place for welding. Moreover, difficulty is often encountered in moving the prior line-up clamps through curved pipe sections because of the very small clearance normally provided between the pipe engaging clamping shoes and the internal surfaces of the pipe.

Although many attempts, have been made to overcome the foregoing and other disadvantages of the prior art clamps, non, as far as is known, has been provided which has been entirely satisfactory in commercial operations.

Accordingly, it is an object of the present invention to provide an apparatus for axially aligning adjacent pipe ends which is capable of exerting very high radial forces on the inner circumference of the pipe ends to force each into a truly circular configuration.

Another object of the invention is the provision of apparatus for aligning pipe ends which is capable of clamping the end of a set-in pipe and drawing it into abutting, axially aligned relationship with the pipe end to which it is to be joined.

Another object of the invention is to provide an internal pipe line-up clamp which may be quickly and automatically positioned and clamped at the end of the welded in-pipe section in position for receiving the setin pipe section.

Still another object of the present invention is to provide a pipe line-up clamp which functions to (a) securely clamp and round out the open end of the welded-in pipe in an initial clamping action, (b) clamp the set-in pipe end after it is brought into rough end-toend alignment with the welded-in pipe, (c) draw the set-in pipe towards the welded-in pipe to bring the end faces of the two pipes into engagement, (d) securely clamp and round out the end of the set-in pipe in a secondary clamping action and, finally, (e) back-space the end face of the set-in pipe a predetermined distance of the welded-in pipe end face to provide a uniform gap between the adjacent pipe end faces while still maintaining the pipe walls in accurate alignment.

Yet another object of the present invention is the provision of apparatus for aligning pipe ends which incorporates pipe-engaging clamping elements capable of relatively large retractive radial movement from an operative to a non-operative position thereby permitting the clamp to traverse curved pipe sections without damage to the pipe or clamping elements.

A still further object of the invention is to provide apparatus for positioning and aligning pipe ends which is relatively inexpensive .to manufacture, simple to operate and rugged and durable in use.

According to the invention, these and other objects and advantages are obtained by an internal line-up clamp which incorporates a pair of interconnected but independently operable clamping; assemblies, each of which includes a set of radially movable pipe engaging shoes adapted to clampingly engage the inner circumferences of a pair of pipe sections in the zones adjacent their ends. At least two axially movable pneumatic actuators are operatively associated with each set of clamping shoes in a manner such that axial movement of the actuators effects radial movement of the shoe set with which they are associated. The clamping assemblies are interconnected by a plurality of axially extending rods which are adapted to maintain the assemblies in axial alignment while permitting them to be moved axially with respect to each other a limited distance. A fifth pneumatic actuator means is provided for effecting such reciprocalaxial movement of the clamp assemblies.

The double actuator means associated with each set of pipe engaging shoes enables each shoe set to be actuated independently and it also permits imposition of clamping forces which can be selectively increased through at least two stages to a level sufficiently great to round out large diameter, high strength pipe sections without difficulty. In a preferred embodiment of the clamp, the high clamping force capability of the compound actuator means is transmitted to the pipe engaging clamping shoes by means of a plurality of tandem pivot links which are adapted for retraction radially inwardly when the clamp is in a non-operative or pipetraversing state, thus ensuring ample clearance between the clamp shoes and the inner wall of the pipe through which it is traversed.

An another preferred aspect, the clamp incorporates pneumatically actuated drive means for propelling the clamp axially forwardly through a pipeline section together with associated control means for automatically stopping, reversing and positioning the clamp at the open end of the welded-in pipe section in position to receive the next set-in pipe section. The invention is explained in detail hereinbelow by reference to a specific clamp apparatus incorporating the features of the invention. Such apparatus is not meant to be limiting inasmuch as it will be understood that it constitutes but one of the ways in which the principles of the invention may be applied.

In thedrawings, wherein like reference numerals indicate line parts in the various views:

FIG. 1 is a perspective view of an embodiment of the clamp apparatus of the invention, with some parts omitted for sake of clarity, showing the clamp traversing a pipe section;

FIG. 2 is a side elevation, with some parts omitted and portions broken away, showing the clamp in operative position in a pair of adjacent pipe sections;

FIG. 3 is a partial longitudinal sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is a longitudinal sectional view similar to FIG. 3 but with the pipe clamping shoes and supporting linkages in a retracted position for travel through a pipe section;

FIG. 5 is a transverse sectional view, with portions broken away, taken along the line 55 of FIG. 3.

'FIG. 6 is a detail exploded perspective view of a clamp shoe supporting link assembly;

FIG. 7 is a fragmentary longitudinal sectional view showing one form of clamping shoe configuration;

FIG. 8 isa fragmentary longitudinal sectional view showing another form of clamping shoe configuration;

FIG. 9 is a transverse sectional view along the lines 99 of FIG. 2;

FIG. 10 is a longitudinal view along the line 10-10 of FIG. 9;

FIG. 11 is a longitudinal view along the line 11-l1 of FIG. 9;

FIG. 12 is an end elevation view along the line 12- 12 of FIG. 1 1;

FIG. 13 is a side elevation detail, with portions broken away, showing the clamp back-stop mechanism;

FIG. 14 is an end elevation along the line 14-14 of FIG. 1 showing elements of the clamp control mechanism;

FIG. 15 is an end elevation along the line l5-15 of FIG. 2 showing the manually actuable pilot valves for controlling the clamp functions;

FIGS. 16, 17, 18 and 19 depict schematically the operating sequence of the clamp; and

FIGS. 20, 21 and 22 are diagrammatic representations of the pneumatic control system for the clamp.

In FIG. 1, the internal pipe line-up clamp of the invention, indicated generally by the reference numeral 10, is shown disposed in an intermediate position within a first pipe line section P to which another pipe section P (FIG. 2) is to be welded in end-to-end relationship. The function of the clamp 10 is to grip the adjacent ends of pipes P and P and position and maintain them securely in a precisely aligned and spacedapart end-to-end relationship for welding.

The clamp 10 comprises six basic sub-assemblies:

1. The pipe engaging members or clamping shoe sets;

2. the clamping shoe support linkages;

3. the clamping shoe actuation mechanisms;

4. the set-in pipe positioning and back-spacing mechanisms;

5. the clamp drive and conveying mechanisms; and

6. the clamp control mechanisms.

Referring first to FIGS. 1-6, there are two clamping shoe sets 14, 15 each comprising a plurality of peripherally spaced clamping shoes 16. As best shown in FIGS. 3, 4 and 5, the shoes 16 are removably secured to mounting blocks 20 by means of tenons 21 and counter-sunk screws shown, for example, at 23 in FIG. 5. Peripheral spaces 24 are provided between the adjacent shoes 16 in each clamp set 14, 15 to permit their radial movement in operation. By the use of removable shoes, shoes with different radial thicknesses may be selectively used to adapt the clamp for use with pipe sections of different diameters. Shoes 16 may also be provided with different types of facings such as hard rubber, low friction plastics etc. Also, according to the invention, the shoes 16 may have different peripheral configurations to adapt them for use with thick wall or thin wall pipes. For thick wall pipes, as shown in FIG. 7, shoes 16 are formed with forward portion 17 of greater radial thickness than the rearward portion 18 so that when the shoes are moved into engagement with pipe sections P P the forward portions 17 contact the pipe surface first. For use with thin wall pipe sections, as shown in FIG. 8, shoes 16 preferably are formed with slightly curved rearward portion 19 which has a radial diameter slightly greater than that of the forward portion 19': this enables imposition of the main clamping pressure at a point back from the pipe end thereby ensuring that the pipe can be firmly clamped without over-stressing it at its outer end.

Each of clamping shoe mounting blocks 20 is formed with a tandem clevis 30 on its radially inwardly disposed side. Theclevises 30 are pivotally connected by means of transverse pins 31 with the radially outer ends of tandem link pairs 32. Blocks 20 are also pivotally connected to generally axially and outwardly directed link arms 34, the other ends of which are pivotally connected as indicated at 38 to the radially outer end of fixed radial brackets 40 in the case of shoe set 14 and as indicated at 39 to the outer end of fixed radial bracket 41 in the case of shoe set 15. Brackets 40, 41 are secured to the actuator housings of the clamp. In operation, thelink arms 34 permit radial movement of shoe sets l4, 15 but limit axial movement thereof with respect to brackets 40 and 41, respectively. It should be noted, however, that shoe sets 14 and 15 are coaxial but mounted independently of each other so that in operation, although they are maintained in axial alignment, they can be moved axially with respect to each other as is explained later.

The radially inner ends of the link pairs 32 of each shoe set are pivotally connected bymounting blocks 42 to axially movable piston rod element, indicated generally 45 for set 14 and at 46 for set 15, so that the link pairs 32 convert axial movement of the piston rod elements 45, 46 into radial movement of the clamping shoe sets 14 and 15 respectively.

Each link pair 32 is comprised of first link members 43 and second link members 44 pivotally mounted between shoe support blocks and piston rod mounting blocks 42 in a tandem arrangement. Link pairs 32 are constructed with a limited arc pivot joint at their mid-points which permits them to be selectively positioned in an extended or operative position as shown in FIG. 3 or in a retracted or non-operative position as shown in FIG. 4. This retractility of the link pairs 32 ensures ample clearance between the clamping shoe sets 14, 15 when the clamp is traversing a pipe section, particularly a curved pipe section, after a weld is completed and the clamp is being moved to a new joint. The structural details of each link pairs 32 can be seen by reference to FIG. 6. FIG. 6 shows the construction of one link pair 32 associated with shoe set 15, but it will be appreciated that each of the link pairs 32 (eight for each clamp shoe set in the embodiment illustrated) have an identical construction and that the linkpairs associated with shoe set 14 are merely reversed with respect to their axial disposition. Link pairs 32 include tandem links 43, 44 each of which is formed of two half-links 50, and 51, 51'. The inwardly disposed ends of the half-links 50, 50 and 51, 51' are formed with arcuate saddle portions as indicated at 49, 49' adapted to seat on central pins 54. Pins 54 are provided with two holes as shown at 55 through their diameters adapted to receive bolts such as 56 in counterbored relationship. Threaded holes 57 corresponding to holes 55 are provided in half link portions 50', 51' to receive bolts 56. The arcuate saddle elements 49, 49' each is comprised of segments of less than 180 so that there is an open segment, as indicated at 60 in FIGS. 3 and 4, in the pivot joint between each half link which permits limited pivotal movement of the half links from the extended of in line position as shown in FIG. 4. Halflinks 50, 51 are secured together for limited pivotal movement by means of spacer rings 62 which circumscribe pins 54 and are attached to half links 50, 51 by means of screws such as shown at 63 threaded into holes 64.. Links 44, 43 are connected at their central pivot joints by means of link element 65 which, in turn, is secured to pins 54 by means of retainer ring 66and co-operating grooves 67 formed in pins 54. It can be noted that central pivot joints are arranged such that the link pairs 32 associated with each shoe set can pivot from the extended position to the retracted position only to the left in the case of link pairs associated with clamp shoe set 14 and, in the case of link pairs associated with shoe set 15, as shown in FIGS. 3 and 4 only to the right.

In their normal pipe traversing disposition, link pairs 32 are in a retracted condition as shown in FIG. 4 to provide maximum clearance between clamping shoe sets l4, l5 and the inner circumference of the pipe section through which the clamp 10 is moved preparatory to positioning between pipe joints P P for clamping the pipe ends for welding. Means are provided, therefore, for effecting movement of the link pairs 32 from their retracted position to their extended position. This means includes lever arms 70 fixed at a slight angular disposition to the radially inward ends of links 44. The other ends of levers 70 are provided with saddle elements 72 which are pivotally connected by means of pins 74, 75 to annular axially movable spider members 76 (see FIG. 5) and 77 which,in turn, are fixed to annular piston rod elements 78, 79 which are adapted for axial reciprocatory movement along cylindrical central rod 80.

Piston rod elements 78, 79 are fixed to annular pistons 81, 82 respectively which are positioned for axial reciprocal movement within annular cylinders 83, 84. Suitablepiston rod sealing rings 85 and piston sealing rings 86, are provided to ensure a pressure tight seal between the relatively movable elements. Compression springs 90, 91 between the piston and cylinder end walls bias pistons 81, 82 to the right and left respectively thereby providing a spring assist for the movement of pistons 81, 82 and associated pivot links to the straight or extended position, as shown in FIG. 3. Pressurization of cylinders 83, 84 throughconduits 92, 93 respectively will move pistons 81, 82 towards the right and left respectively with accompanying extension of link pairs 32, as shown in FIG. 3, with assist springs 90, 91 ensuring that this action will take place with relatively low pressure.

As noted above, axial movement of annular piston rod elements 45 and 46 effects radial movement of shoe sets 14, 15 respectively through the medium of the link pairs 32. According to the invention, axial move ment of piston rod elements 45, 46 is effected by means of adual actuator arrangement associated with each shoe set 14 and 15. This permits imposition of staged and large clamping pressures on the inner circumference of the pipe sections P P For the purposes of this description, the four clamp shoe actuators are referred to herein from time to time as actuators A, B, C and D. Actuators A and B are operatively associated with shoe set 14 and actuators C and D with shoe set 15. Referring particularly to FIGS. 3 and 4, actuator A is indicated generally by numeral 100, actuator B by numeral 102, actuator C by numeral 104 and actuator D by numeral 106.

The structure and operation of actuators 104 and 106 (C and D) will be described first. Actuator D includes an annular cylinder 110 defined by housing comprising a first casing member 11 1 and a second casing member 112 secured together, such as by bolts (not shown) through inset peripheral flanges indicated at 113, .114. Positioned for axial movement within cylinder 110 is an annular piston member 115 in the form of a radially disposed plate peripherally secured in a pressure-tight manner by resilient diaphragm 116 clamped between flanges 113 and 114. The radially inner end of piston 115 is integral with sleeve member 117 which is axially movable with respect to casing members 111 and 112 and which functions as a piston rod for piston 1 15. Suitable pressure-tight seals 118 are provided between sleeve member 117 and casing members 111 and 112 to prevent air loss when cylinder 1 10 is pressurized.

Actuator 104 (C) includes annular casing member 120 which is integral with casing member 112 and has an inset peripheral flange 121. A second piston 122 in the form of a radially extending annular plate is peripherally secured in a pressure-tight relationship to flange 121 by means of a resilient diaphragm 123 clamped to the flange 121 with ring flange 124. The inner radial end of piston 122 is integral with sleeve 117 and also is fixed to piston rod element 46. An airtight annular chamber 125 is defined between wall casing means 120 and piston 122.

In operation, the introduction of air under pressure into cylinder 110 on the right side of piston 115 will cause piston 1 to move axially to the left as viewed in FIGS. 3 and 4 and this movement will be transmitted by sleeve 1 17 and piston rod element 46 to link pairs 32 to cause, in turn, the clamping shoe set 15 to move into engagement with the inner circumference of pipe section P Also, application of pneumatic pressure to chamber 125 will cause piston 122 to move axially to the left. This serves to increase the force exerted on line pairs 32 and shoe set 15 by virtue of the increasing of the piston area acted on by air pressure. The force resulting from the pneumatic pressure on piston 122 is transmitted through sleeve 117 and piston rod element 46, which are common to both piston 122 and piston 115.

The structure and function of actuators 100 and 102 (A and B) and the mechanism for transmitting the axial movement of these actuators to clamp shoe set 14 for clamping pipe section P is essentially the same as that just described for actuators 104, 106 (C and D) of clamp shoe set 15. The mechanisms are, of course, reversed with respect to their axial dispositions. In addition, it should be noted that for purposes which are explained later, the housing of actuators 100 and 102 is fixed to central rod 80 by means of end cover plate 134 which is secured to the end of rod 80 and to portion 131' of actuator casing member 111, whereas the housing of actuator 104 and 106 is not fixed to rod 80.

The set-in pipe positioning and back-spacing mechanisms of clamp 10 will now be described. In general, according to the invention, this mechanism is provided for the purpose of first clamping and drawing the set-in pipe section P into precise end-to-end abuttingrelationship with the previously welded pipe section P and then back-spacing the set-in pipe P a predetermined distance while retaining the two sets of clamping shoes l4, l5 and the ends of pipes P and P in precise axial alignment. Referring particularly to FIGS. 9, 10, 11 and 12, means are provided for retaining the clamp shoe sets 14, 15 in axial alignment which include a plurality of axially extending rods 150, 151 arranged around and interconnecting the peripheral flanges 121, 124 of actuator 104 with peripheral flanges 121', 124' of actuator 102. As shown in FIG. 10, rods 150 are of cylindrical configuration and have one end fixed in perpendicular relationship to the flange 124 of actuator 102 by means of welding, as shown at 160, and bolted bracket 161. The other end of rod 150 has a reduced cylindrical portion 162 which is slidably fitted in a cylindrical bearing member 163 which is secured to the peripheral flange of actuator 104 by a suitable means such as bolts 164.

As shown in detail in FIG. 11, rods 151 also have one end fixed to peripheral flange 124' of actuator 102 by means of welding at 170 and bolted bracket 171. However, the other end of rods 151 passes through the peripheral flanges 121, 124 of actuator 104 and projects on through the peripheral flanges 114, 113 of actuator 106 as well. Rod 151 has a first reduced-size portion 172 which is slidably received in a bearing member 173 fixed to peripheral flange 124 by means of bracket 174 and bolts 175.

A'stop block 200 is rotatably mounted on a second reduced portion of each shaft 151 between flanges 121 and 114. Stop block 200, together with other elements described later, functions to effect accurate back-spacing of the clamped set-in pipe P a predetermined distance from the clamped welded pipe P after the pipe ends have been brought into precise alignment and abutting relationship. The stop block 200 includes a body portion 201 and a pair of axially extending studs 202, 203 threaded therethrough. Block 200 is held in an axially fixed position on rod 151 by means of a shoulder 210 on shaft 151, spacer 211, a pair of thrust washers 212 and 212' and a lock nut 213, threaded on the rod and abutting a second shoulder 214. A suitable low friction bushing 177 is provided in the peripheral flanges 114, 113 of actuator 106 to slidably receive the outer end portion 176 of rod 151.

Rigidly secured to each block 200 is a pivot arm 220 which is pivotally connected by pin 221 to piston rod 222 of a pneumatic actuator 223 (actuator F). Actuators 223 are pivotally secured to anchor blocks 224 fixed to casing member wall of actuator 104. Two blocks 224 serve to anchor the ends of the four actuators 223 as shown in FIG. 9.

Actuators 223 function to selectively rotate blocks 200 from the position shown in FIG. 1 1 with studs 202, 203 in axial alignment with bolt heads 225, 226 to the position. shown in FIG. 12 in which the studs 202, 203 are not aligned with bolt heads 225, 226. As is described later, rotation of blocks 200 from the latter, non-aligned position to the aligned position enables back-spacing of the set-in pipe P a predetermined distance from the end of welded pipe section P, to provide a precise, controlled-dimension gap between the adjacent pipe ends which facilitate welding.

From the foregoing description, it can be seen that the sets of shoes 14, 15 and associated actuators A, B and C, D, respectively, are retained in axial alignment by rods 151 and but are adapted for axial displacement with respect to each other without loss of axial alignment. Axial displacement of the clamp shoe sets and associated actuators with respect to each other is effected by means of actuator mechanism 250 (actuator E). As shown in FIGS. 3 & 4, actuator 250 consists of an annular cylinder 251 defined by an annular inner end wall 252 which is integral with casing wall 111 of actuator 106 and an outer wall 253 which is secured bymeans of flange 254 to flange 255 of inner wall 252. A piston member 256 which is in the form of an annular, radially extending plate, is positioned in cylinder 252 for axial movement. Piston 256 is peripherally secured in a pressure-tight manner by resilient diaphragm 258 which is also clamped between casing flanges 254,255. The radially inner end of piston 256 is fixed to central rod 80 such that the rod 80 functions as a piston rod for piston 256. Selective introduction of pneumatic pressure to cylinder 251 will axially displace central member 80 either to the left or right in FIG. 4. Since member 80 is fixed to casing end .cover 134 which is fixed to the casing of actuators 100 and 102, axial movement of memberv80 willaxially displace clamp shoe set 14 and its associated actuators 100 and 102 with respect to clamp shoe set 15 and its associated actuators 104 and 106.

Referring again to FIG. 11, it can be seen that axial movement of rods 151 to the left in FIG. 12 will be limited by the engagement of studs 202, 203 with bolt heads 225, 226. Thus, the amount of back-displacement of clamp shoe set 14 with respectto clamp shoe set 15 and the amount of back-spacing of set-in pipe section P from pipe section P can be selectively varied by adjustment of studs 202, 203 in stop blocks 200.

The clamp of the invention includes means for conveying the unit through pipe sections and for automatically positioning the clamp at the forward end of the welded pipe line for receiving andclamping a new pipe section. As can be seen in FIGS. 1 and 2, a plurality of rollers 300 are mounted on the housings of actuators 100 and 106 by means of mounting clevises 301 and brackets 302. Mounted on the casing of rear actuator 106 by means of radial bracket 305 is a drive wheel 310 having a rubber tread tractionsurface and being adapted to engage the interior of the pipe wall beneath the clamp unit in the central region of the pipe section.

Drive wheel 310 is operatively connected with a conventional, instantly reversible air driven motor 311. The motor control mechanism 320 is shown in FIG. 13 and comprises an axially aligned earn 321 mounted on a rod 322 mounted for slidable radial movement in a fixed sleeve 323. A helical compression spring 324 is disposed in sleeve 323 around the upper end 325 of rod 322 such as to normally urge the rod and its cam 321 radially outwardly. A fixed stop 326 and a co-operating keyway 327in the upper section of rod 322 serve to restrict the extent of radial movement of rod322.

The cam 321 is provided with a rearwardly directed and radially extending cam face 328 which is provided for end abutment withthe end surface of the welded pipe line section P and with a forwardly directed oblique cam surface 329 for engagement with the leading edge of the set-in pipeline section P so that, during the positioning of pipe section P about the clamp shoe set 14, the cam 321 will be urged radially inwardly. The purpose of the notch 330 adjacent cam surface 328 will become apparent when the description of the operation of the line-up clamp is given.

Diametrically opposite the keyway 327, the rod 322 is provided with a cam surface 331 which co-operates with a spring return cam actuated pilot valve 332 for the purpose which will become apparent as the description proceeds.

The sleeve 323 is mounted on a shaft 333 which has opposed reduced-size cylindrical portions 334, 334' slidably fitted for limited axial movement in bushed housings 335 and 335'. Housings 335 and 335' are fixed to the peripheral flanges 124' and 124 of actuators 102 and 104, respectively. A helical compression spring 336 is disposed within housing 335 between the end of shaft portion 334 and the face of flange 124' so that shaft 333 is constantly biased to the right as viewed in FIG. 13. A stud 337 is axially threaded into shaft end portion 334 and projects through an opening in flanges 124', 121 with sufficient clearance to permit free axial movement.--Lock nut 338 is provided to adjust and limit axial movement to the right of stud and attached shaft 333. A stud 340 is axially threaded into reduced portion 334' of shaft 333 and projects through an opening in flanges 124 and 121 of actuator 104 with sufficient clearance to permit free axial movement thereof. Stud 340 terminates in a cam member 341 which is operatively associated with spring return, cam operatedpilot valve 343 mounted ona bracket 344 secured between the casing wallsof actuators 104and 106. Axial movement of stud 340 is limited by lock nuts 342.

As shown particularly in FIGS. 1, 2, 14 and 15, the clamp handle and control mechanisms comprise a protectiveframe consisting of tubular frame members 350 fixed to circular frame member 351'which, in turn, is attached by brackets (not shown) to the peripheral flange 113-" of actuator 100. Frame elements 350 exlater. As shown particularlyin FIGS. 2 and 15, as-

sembly 357 includes annular mounting ring 380 fixed co-axially with respect to shaft 354 by means of axially extending support rods 381 secured to cover plate 134. A bracing element 382 is fixed to rods 381 about midway between ring 380 and plate 134. A connecting rod 356 of a length at least equal to the length of the longest pipe section to be welded is removably connected tost'ub shaft 354 by means of a first coupler 358. Rod 356 is connected by a second coupler 359 to an outer stub shaft 360 which is journalled for rotation within frame 361. I

A control handle 363 is fixed to shaft 360 to permit shaft 360 and the connecting rod 356 to be selectively rotated thereby turning stubshaft 354 and associated crank means 355. to actuate the cam operated pilot valves 416, 441 451, 454, 475 and 477. A pointer 364 is also attached to stub shaft 360 to visually indicate, in conjunction with dial 362, the clamp function which is effected at each position of the control handle. A frame 370 and protective end cover 371 are provided to prevent damage to or accidental actuation of the control mechanisms. The circumferentially spaced support rollers 372 are secured around frame 361 to center the control head inpipe section P Referring now to FIGS. 20, 21 and 22, the pneumatic control circuit for clamp 10 includes a two-compartment compressed air supply tank 400 which, as shown in FIGS. 1 and 2 for example, is secured by mounting brackets 401 to the casing wall of actuator 250. A high pressure compartment 402 of tank 400 is connected via conduit 403 through air applied, spring return four-way valve 404 (FIG. 22) and conduit 398 to reverse drive inlet port 397 of drive motor 31 1.

The low pressure compartment 405 of tank 400 is provided with a safety valve 406 and is connected via conduit 407 through non-return valve 408 with conduit v 403. Valve 408 permits flow of air from tank compartment 405 to compartment 402 when the pressure in the latter compartment drops below that of 405.

Low pressure compartment 405 is also connected via conduits 409 and main pressure supply line 410 with the forward drive inlet port 412 of drive motor 311 through the circuit shown in FIG. 22. This circuit includes single air operated spring return three-way valve 413 connected by conduit 414 to spring return pilot valve 343 (see also FIG. 13) which, in turn, is connectedwith the main low pressure air supply line 410. The outlet side of valve 413 is connected through manually operated spring return, pilot valve 416, conduit 417, valve 404 and conduit 418 with the drive motor forward drive inlet port 412. Automatic control pilot valve 332 (see also FIG. 13) is connected via conduit 419 to conduit 417 and via conduit 420 to valve 404 so that actuation of pilot valve 332 actuates valve 404 to shut off the air to conduit 418 and to admit high pressure air through conduit 398 and port 397 to instantly reverse the motor 311.

The pneumatic control circuit for actuators A, B, C,

D, E, and F includes main air supply conduit 440 connecting low pressure tank compartment 405 with the actuator cylinders through the circuit shown in FIG. 21. Referring first to actuator B, main air supply line 440 is connected through manually operated pilot valve 441, conduit 442, double air operated four-way valve 443 and conduit 444 with cylinder 135' of actuator B. Valve 443 is also connected via conduit 445 with conduit 450. Conduit 450 is connected to air supply line 440 through cam operated pilot valve 451 and is connected with the right side of cylinder 110' of actuator A through air supply spring return four-way valve 452 and conduit 453.- Valve 452 is also connected to cam operated pilot valve 454 through conduit 456. Valve 452 is connected by conduit 455 to the left side of cylinder 110' of actuator A. Valve 443 is also connected through conduit 457 with the right side of cylinder 83 (see also FIG. 3) of actuator G. The left side of cylinder 83 is connected via conduit 92 with cylinder 125'. Cylinder 125 of actuator C is connected via conduit 460 with single air operated spring return four-way valve 461 and to manually operated air return threeway valve 462. Valve 462 is also connected to conduit 450 via conduit 463. Valve 461 is connected through conduit 364 with the right side and through conduit 365 with the left side of cylinder 110 of actuator D. Conduit 365 also is connected through conduit 366 with the left side of cylinder 84 of actuator G. The right side of cylinder 84 is connected via conduit 93 with cylinder 125.

Conduite 470 and 471 connect the right and left sides respectively, of cylinder 251 of actuator E with double air operated four-way valve 472. Valve 472 is connected through conduit 474 with manual cam operated pilot valve 475 and is also connected via conduit 476 to manual cam operated valve 477 which, in turn, is connected with air supply line 440. Switch 477 is connected to the extend and retract sides of actuator F via conduits 483 and 484 respectively. Finally, valve 480 is also connected to air supply line 440 through conduit 450 and switch 451.

For purposes of explaining the operation of the clamp, it will be assumed that welding of two adjacent pipes has been completed, the clamping pressure has been released and the clamp 10 is ready to be moved to the forward end of the pipe line for clamping a new setin pipe joint P; for welding to the previously welded pipe section P At this point, the pipe clamping shoe sets 14 and 15 will be in a fully retracted position as shown structurally in FIG. 4 and schematically in FIG. 16. The clamp backstop mechanism 320 will be in the retracted position with the cam member 321 abutting the inner surface of the pipe section P also as schematically illustrated in FIG. 16. To initiate operation of the pipe clamp from this point, motor 311 is actuated by turning control handle 363 to actuate pilot valve 416 admitting air through valve 404 to the forward drive inlet 412 of motor 311 thereby driving the clamp forward. When the clamp 10 reaches the front end of pipe section P cam 321 and rod 323 move radially outwardly under the action of spring 324 to the position shown schematically in FIG. 17. This movement actuates pilot valve 332 which admits air through conduit 420 to valve 404 closing conduit 418 and opening conduit 398 to admit high pressure air to motor 311 through reverse drive inlet port 397. The reverse drive of motor 311 continues until surface 328 of cam 321 is forced into engagement with the end of pipe section P as shown in FIG. 18. This causes shaft 333 carrying cam member 341 to be pushed to the left against the bias of spring 336 (FIG. 13). This, in turn, causes actuation of pilot valve 343, also as shown in FIG. 18, which admits air to valve 413 to shut off the high pressure, reverse drive air supply and stop the motor 311.

Valve 462 is then opened, either manually or by pilot valve means which is automatically actuated when the reverse drive air supply is cut off. This admits air to cylinder 125 of actuator C and to the right side of cylinder 110 of actuator D. Pressurizat'ion of cylinder 125 also admits air pressure to cylinder 84 via conduit 93 (see FIG. 3). This causes piston 82 of actuator G to move to the left, as viewed in FIGS. 3 and 4, straightening link pairs 32 to their extended or operative positions, as shown in FIG. 3. This straightening action occurs before sufficient pressure is built up in cylinder 125 to cause axialmovement of piston 122 because the assistance provided by spring 91 and also because much less pressure is required to actuate piston 82 in cylinder 84 than is required to move piston 122 of actuator C. After links 32 are extended, pressure buildup in actuators C and D continues and causes pistons 1 15 and 112 to move to the left forcing clamp shoe set 15 into engagement with pipe section P The set-in pipe section P is then introduced over projecting clamp shoe set 14 as shown in FIG. 18, and actuator B is activated by pilot valve 441 which opens valve 443 to admit air through conduit 444 to cylinder 125. This results first in the straightening of link pairs 32 by actuation of piston 81 of actuator G in a similar manner to that just described for link pairs 32 and piston 82 and, second, in the engagement of clamp shoe set 14 against pipe P as shown in FIG. 18. At this point, actuator A has not yet been pressurized and pipes P and P are not necessarily in alignment. Actuator E is next pressurized by actuation of pilot valve 475 which opens valve 472 to admit air through conduit 471 to the left side of cylinder 251. This causes piston 256 to move to the right pulling clamp shoe set 14 and clamp set-in pipe section P into end abutting relationship with pipe section P Pilot valve 454 is then activated to open valve 452 to'pressurize the left side of piston 1 15 of actuator A thereby forcing piston 1 15' to the right, increasing the pressure of clamp shoe set 14 to round out the end of pipe P and ensure true axial alignment with the end of pipe P Next, actuator F is pressurized by an activation of pilot valve 477 which opens valve 480 to cause piston rod 222 to extend. This results in rotation of stop blocks 200 such that studs 202, 203 are in axial alignment with bolt heads 225, 226 as shown in FIG. 1 1. Actuation of pilot valve 477 simultaneously opens valve 472 to effect pressurization of the right side of cylinder 251 of actuator E thereby causing piston 256 to move to the left until studs 202, 203 come into engagement with bolt heads 225, 226 as shown in FIG. 11. By selective adjustment of studs 202, 203, pipe section P will be spaced back from pipe section P as shown in FIG. 19, a distance which provides an optimum gap for welding having regard to the pipe diameters, type of welding system employed, etc. Also, as shown inFIG. l9 and FIG. 2, with the clamp 10 in this position cam 321 is disposed with notch 330 adjacent the gap between the pipes P and P so that cam 321 will not interfere with the welding operation.

The welding operation is then carried out. At completionof the welding operation, pilot valve 451 is activated and actuators A, D, G and G are pressurized so as to cause pistons 115, 82 and 115, 81 to move to the left and right respectively thereby retracting the clamp shoe sets 14 and 15. At the same time, cylinders 125' and 125 are vented to the atmosphere and piston rod 222 of actuator F is retracted to rotate the stop blocks 200 to the non-aligned position shown in FIG. 12. Also, cylinder 251 is pressurized via conduit 470 to fully extend piston 256 to the left.

The line-up clamp of the invention has numerous important advantages over the clamps heretofore known and used in the pipeline construction industry. Foremost of these advantages is the adaptability of the clamp for use with automatic pipe welding systems. In order to function effectively, automatic welding requires extremely accurate alignment of the adjacent pipe ends as well as a uniform gap between the opposed surfaces which are to be joined. Heretofore, in order to obtain the necessary uniformity of alignment and spacing, it has been necessary to first clamp thepipes then cut or grind the ends to provide the desired gap. This expensive and time-consuming procedure can be eliminated through use of the clamp of the present invention.

What we claim as new and desire to protect by Letters Patent of the United States is:

l. A line-up clamp for aligning a pair of pipeline sections by engagement with their inner surfaces which comprises: a first set of radially movable pipe engaging shoes adapted to engage the inner circumference of the first of said pair of pipeline sections, a second set of radially movable pipe engaging shoes adapted to engage the inner circumference of the second of said pair of pipeline sections, a first housing substantially coaxial with said first set of pipe engaging shoes and a second housing substantially coaxial with said second set of pipe engaging shoes, means interconnecting said first and second housings and maintaining said housings in axial alignment while enabling limited axial movement of said housingswith respect to each other; actuator means for effecting reciprocal axial movement of said first and second housings with respect to each other; first and second pairs of fluid driven actuators mounted for reciprocatory movement in said first and second housings, first and second drive members operatively associated with said first and second actuator pairs respectively and adapted for reciprocal axial movement independently of each other, a first set of link members operably interconnecting said first drive means with said first set of clamping shoes such that axial movement of said drive means is converted to radial movement for actuation of said first set of pipe clamping shoes, a second set of link members operably interconnecting said second drive means with said second clamping shoe sets such that axial movement of said drive means is converted to radial movement for actuation of said second set of pipe clamping shoes.

2. An internal line-up clamp as claimed in claim 1 in which said interconnecting means includes a fifth actuator means adapted to effect selective axial displacement of said first housing and associated set of pipe engaging shoes with respect to said second housing and associated set of pipe engaging shoes whereby said pipeline sections may be moved into and away from end abutment with each other.

3. A clamp as claimed in claim 1 in which said links are arranged and constructed for radial retraction and extension to non-operative and operative positions respectively.

4. A clampas claimed in claim 1 which additionally comprises drive means for driving said clamp axially forward through said pipeline section, control means for controlling the operation of said drive .means, backstop means comprising a radially movable cam member adapted to normally abut said inner surface of said pipeline section, means urging said cam member radially outwardly, means sensitive to radial outward movement of said cam member radially outwardly beyond said inner surface of said pipe section and adapted on such movement of said cam member to reverse said drive means to drive said clamp rearwardly a predetermined distance.

5. An internal line-up clamp as claimed in claim 3 in which said links have pivotally connected inner and outer sections, and means being provided to maintain each of said inner sections in radially alignment with their respective outer section and to permit said inner and outer sections to pivot with respect to each other whereby said pipe engaging members may be retracted substantially radially inwardly.

6. An internal line-up clamp as claimed in claim 5 including pneumatic actuator means operatively connected with said links and adapted to selectively pivot said links into radial alignment.

7. An internal line-up clamp for aligning a pair of pipeline sections by engagement with their inner surfaces which comprises an elongated axial cylindrical member, a first set of radially movable pipe engaging members adapted to engage the inner circumference of the first of said pair of pipeline sections, a second set of radially movable pipe engaging members adapted to engage the inner circumference of the second of said pair of pipeline sections, a first sleeve circumscribing and axially slidable along said axial cylindrical member, first actuator housing means circumscribing said axial cylindrical member in a fixed position with respect thereto, first and second actuator means in said first housing means and connected with said first sleeve for effecting reciprocal axial movement of said first sleeve along said axial cylindrical member, a first set of generally radial linkages interconnecting said first sleeve and said first set of radially movable pipe engaging members such that axial movement of said first sleeve effects radial movement of said first set of pipe engaging members, a second sleeve circumscribing and axially slidable along said axial cylindrical member, second actuator housing means circumscribing said axial cylindrical member and axially movable with respect thereto, third and fourth actuator means in said second housing means and connected with said second sleeve for effecting reciprocal movement of said second sleeve along said axial cylindrical member, a second set of generally radial linkages interconnecting said second sleeve and said second set of radially movable pipe engaging members such that axial movement of said second sleeve effects radial movement of said second set of pipe engaging members, a plurality of circumferentially spaced axially extending rod elements interconnecting said first and second actuator housings and maintaining them in axial alignment while permitting limited axial movement of said housings with a respect to each other, and fifth actuator means connected with said axial cylindrical member and adapted to effect reciprocal axial movement of said cylindrical member with respect to said second actuator housing means.

16 with said first of said pair of pipe sections, whereby actuation of said third actuator means causes limited frictional engagement of said second set of pipe engaging members with said second of said pair of pipe sections, whereby subsequent actuation of said fifth actuator causes relative axial movement of said first and said second sets of said pipe engaging members until said pair of pipe sections are in at least partial joint end abutment, whereby subsequent relative axial movement of said first and said second sets of pipe engaging members continues until said pair of pipe sections are in substantially peripherally complete end abutment with any necessary sliding movement of said second of said pair of pipe sections with respect to said second set of pipe engaging members and whereby actuation of said f0 th actuator means in a final clampin operatron e ects secure engagement of said secon set of pipe engaging members with said second of said pair of 8. The clamp as claimed in claim 7 including adjustable stop-block means associated with said axially extending rod elements and adapted for limiting axial movement of said rod elements such that the first housing and associated first set of clamp engaging members may be backspaced a predetermined distance from the second housing and associated second set of pipe engaging members by extension of said fifth actuator.

9. An internal line-up clamp as claimed in claim 7 in which said first, second, third, fourth and fifth actuator means are independently operable whereby actuation of said first and second actuator means effects secure engagement of said first set of pipe engaging members pipe sections whereby said second and said first pipe sections are securely held in end-abutting relationship.

10. The internal line-up clamp as claimed in claim 9 in which means are provided whereby actuation of said fifth actuator effects axial separation of said securely held end-abutting section to provide a uniform gap of predetermined width between said pipe sections.

11. An internal line-up clamp as claimed in claim 7 including drive means for driving said clamp axially forwardly through said pipe section, control means for controlling the operation of said drive means and for controlling the operation of said radially movable pipe engaging members, end-sensing means comprising a radially movable member adapted to normally abut the inner surface of said pipeline section, means urging said end-sensing means radially outwardly, means sensitive to radially outward movement of said end-sensing means radially outwardly beyond said inner surface of said pipeline section and adapted, on such movement of said end-sensing means, to actuate said drive means to prevent further forward movement of said clamp axially through said pipeline section.

12. An internal line-up clamp as claimed in claim 1 l in which said meanssensitive to said radial outward movement of said end-sensing means beyond said inner surface of said pipe section is also adapted, on such movement of said end-sensing means, to actuate said first and second actuators for clampingly engaging said first set of pipe engaging members with said first pipe section. 

1. A line-up clamp for aligning a pair of pipeline sections by engagement with their inner surfaces which comprises: a first set of radially movable pipe engaging shoes adapted to engage the inner circumference of the first of said pair of pipeline sections, a second set of radially movable pipe engaging shoes adapted to engage the inner circumference of the second of said pair of pipeline sections, a first housing substantially coaxial with said first set of pipe engaging shoes and a second housing substantially coaxial with said second set of pipe engaging shoes, means interconnecting said first and second housings and maintaining said housings in axial alignment while enabling limited axial movement of said housings with respect to each other; actuator means for effecting reciprocal axial movement of said first and second housings with respect to each other; first and second pairs of fluid driven actuators mounted for reciprocatory movement in said first and second housings, first and second drive members operatively associated with said first and second actuator pairs respectively and adapted for reciprocal axial movement independently of each other, a first set of link members operably interconnecting said first drive means with said first set of clamping shoes such that axial movement of said drive means is converted to radial movement for actuation of said first set of pipe clamping shoes, a second set of link members operably interconnecting said second drive means with said second clamping shoe sets such that axial movement of said drive means is converted to radial movement for actuation of said second set of pipe clamping shoes.
 2. An internal line-up clamp as claimed in claim 1 in which said interconnecting means includes a fifth actuator means adapted to effect selective axial displacement of said first housing and associated set of pipe engaging shoes with respect to said second housing and associated set of pipe engaging shoes whereby said pipeline sections may be moved into and away from end abutment with each other.
 3. A clamp as claimed in claim 1 in which said links are arranged and constructed for radial retraction And extension to non-operative and operative positions respectively.
 4. A clamp as claimed in claim 1 which additionally comprises drive means for driving said clamp axially forward through said pipeline section, control means for controlling the operation of said drive means, backstop means comprising a radially movable cam member adapted to normally abut said inner surface of said pipeline section, means urging said cam member radially outwardly, means sensitive to radial outward movement of said cam member radially outwardly beyond said inner surface of said pipe section and adapted on such movement of said cam member to reverse said drive means to drive said clamp rearwardly a predetermined distance.
 5. An internal line-up clamp as claimed in claim 3 in which said links have pivotally connected inner and outer sections, and means being provided to maintain each of said inner sections in radially alignment with their respective outer section and to permit said inner and outer sections to pivot with respect to each other whereby said pipe engaging members may be retracted substantially radially inwardly.
 6. An internal line-up clamp as claimed in claim 5 including pneumatic actuator means operatively connected with said links and adapted to selectively pivot said links into radial alignment.
 7. An internal line-up clamp for aligning a pair of pipeline sections by engagement with their inner surfaces which comprises an elongated axial cylindrical member, a first set of radially movable pipe engaging members adapted to engage the inner circumference of the first of said pair of pipeline sections, a second set of radially movable pipe engaging members adapted to engage the inner circumference of the second of said pair of pipeline sections, a first sleeve circumscribing and axially slidable along said axial cylindrical member, first actuator housing means circumscribing said axial cylindrical member in a fixed position with respect thereto, first and second actuator means in said first housing means and connected with said first sleeve for effecting reciprocal axial movement of said first sleeve along said axial cylindrical member, a first set of generally radial linkages interconnecting said first sleeve and said first set of radially movable pipe engaging members such that axial movement of said first sleeve effects radial movement of said first set of pipe engaging members, a second sleeve circumscribing and axially slidable along said axial cylindrical member, second actuator housing means circumscribing said axial cylindrical member and axially movable with respect thereto, third and fourth actuator means in said second housing means and connected with said second sleeve for effecting reciprocal movement of said second sleeve along said axial cylindrical member, a second set of generally radial linkages interconnecting said second sleeve and said second set of radially movable pipe engaging members such that axial movement of said second sleeve effects radial movement of said second set of pipe engaging members, a plurality of circumferentially spaced axially extending rod elements interconnecting said first and second actuator housings and maintaining them in axial alignment while permitting limited axial movement of said housings with respect to each other, and fifth actuator means connected with said axial cylindrical member and adapted to effect reciprocal axial movement of said cylindrical member with respect to said second actuator housing means.
 8. The clamp as claimed in claim 7 including adjustable stop-block means associated with said axially extending rod elements and adapted for limiting axial movement of said rod elements such that the first housing and associated first set of clamp engaging members may be backspaced a predetermined distance from the second housing and associated second set of pipe engaging members by extension of said fifth actuator.
 9. An internal line-up clamp as claimed in claim 7 in which said first, second, third, fouRth and fifth actuator means are independently operable whereby actuation of said first and second actuator means effects secure engagement of said first set of pipe engaging members with said first of said pair of pipe sections, whereby actuation of said third actuator means causes limited frictional engagement of said second set of pipe engaging members with said second of said pair of pipe sections, whereby subsequent actuation of said fifth actuator causes relative axial movement of said first and said second sets of said pipe engaging members until said pair of pipe sections are in at least partial joint end abutment, whereby subsequent relative axial movement of said first and said second sets of pipe engaging members continues until said pair of pipe sections are in substantially peripherally complete end abutment with any necessary sliding movement of said second of said pair of pipe sections with respect to said second set of pipe engaging members and whereby actuation of said fourth actuator means in a final clamping operation effects secure engagement of said second set of pipe engaging members with said second of said pair of pipe sections whereby said second and said first pipe sections are securely held in end-abutting relationship.
 10. The internal line-up clamp as claimed in claim 9 in which means are provided whereby actuation of said fifth actuator effects axial separation of said securely held end-abutting section to provide a uniform gap of predetermined width between said pipe sections.
 11. An internal line-up clamp as claimed in claim 7 including drive means for driving said clamp axially forwardly through said pipe section, control means for controlling the operation of said drive means and for controlling the operation of said radially movable pipe engaging members, end-sensing means comprising a radially movable member adapted to normally abut the inner surface of said pipeline section, means urging said end-sensing means radially outwardly, means sensitive to radially outward movement of said end-sensing means radially outwardly beyond said inner surface of said pipeline section and adapted, on such movement of said end-sensing means, to actuate said drive means to prevent further forward movement of said clamp axially through said pipeline section.
 12. An internal line-up clamp as claimed in claim 11 in which said means sensitive to said radial outward movement of said end-sensing means beyond said inner surface of said pipe section is also adapted, on such movement of said end-sensing means, to actuate said first and second actuators for clampingly engaging said first set of pipe engaging members with said first pipe section. 